One of the things I got tired of was the same jokes always upvoted to +5 funny, whereas tired memes are discouraged here.
Slashdot was a little bit messy,and less obsessed with facts and technical accuracy, and with being civil and polite, but it was also, well, more human I think. And being a bit messy is ok, as long as most people recognize it (including the people messing about ) and mark things as such for those who don't (the funny, flamebait, etc tags).
Which is a shame, because smart folks are often some of the funniest.